The present invention relates to traction-drive elevator systems, and more particularly relates to gearless machines for such systems.
A conventional traction-drive elevator system includes a car, a counterweight, two or more ropes interconnecting the car and counterweight, a traction sheave to move the ropes (and, thus, the car and counterweight), and a machine to rotate the traction sheave. The machine may be either geared or gearless. In a geared machine a gear train is used to achieve the desired output speeds and torque. In a gearless machine, on the other hand, the traction sheave is mounted directly to the output shaft of the motor. As a result, gearless machines are generally quieter, more reliable, and easier to maintain than the geared versions, although the gearless machines generally must be larger and more expensive to operate at acceptably low speeds while maintaining sufficient torque.
Adding to the expense associated with a typical gearless machine, the traction sheave must be positively connected to the output shaft of the motor. This adds steps and/or materials to the assembly process. Also, the bearings that support the output shaft must also bear the loads carried by the traction sheave. Once the sheave and bearings are mounted to the output shaft, the bearings are mounted on bearing stands, which have openings to support the bearings (and thus the load that carried by the bearings). With the bearings in the openings and the shaft in place, the position of the bearing stands must be carefully adjusted to achieve proper bearing alignment. This further complicates the assembly process.
Thus there is a need in the art to address one or more of the foregoing size, cost or assembly drawbacks of traditional gearless machines.
The present invention addresses the foregoing needs in the art by providing, in various aspects, an improved hoist machine and an improved assembly process.
In one aspect of the invention, a hoist machine is provided for an elevator system that includes an elevator car and a rope, connected to the elevator car and by which the elevator car is hoisted. The hoist machine includes a hoist motor, having an output shaft on which is disposed a traction sheave for frictionally engaging and moving the rope. At least two bearings support and guide the output shaft. When viewed in an axial direction of the output shaft, a profile of the traction sheave can be circumscribed by a profile of at least one of the bearings.
It is preferred that the one of the bearings having the profile that can circumscribe the profile of the traction sheave, is the one of the bearings that is closer to the hoist machine. It is even more preferred that the profile of the traction sheave can be circumscribed by profile of each of the bearings.
In one embodiment, the traction sheave comprises a traction surface having a pitch diameter and at least two annular flanges projecting from the traction surface, wherein the flanges define the profile of the traction sheave. The assembly can also include a single bearing frame, having both a proximal opening and a distal opening aligned with one another for respectively receiving and supporting one of the bearings. Additionally, the traction sheave and the output shaft can be of integral, unitary construction.
Another aspect of the present invention relates to a method of assembling a hoist machine for an elevator system that includes an elevator car and a rope, connected to the elevator car and by which the elevator car is hoisted. The method includes the steps of providing (i) a hoist motor rotor, having an output shaft on which is disposed a traction sheave for frictionally engaging and moving the rope, and (ii) a bearing frame, having a proximal opening and a distal opening aligned with one another for receiving and supporting bearings that rotationally support the output shaft. The output shaft is inserted through the proximal opening so that the traction sheave passes through the proximal opening. With the bearings disposed on the output shaft, the output shaft is further inserted toward the distal opening so that one of the bearings fits into the distal opening and the other of the bearings fits into the proximal opening.
Preferably, throughout the inserting steps, the proximal and distal openings remain fixed positionally relative to one another. It is also preferred that the traction sheave be disposed between the bearings on the output shaft during the inserting step, so that the one bearing passes through the proximal opening before the traction sheave passes through the proximal opening. Alternatively, at least during the continuing to insert step the traction sheave is disposed between the bearings on the output shaft.
In yet another aspect of the invention, a hoist machine is provided for an elevator system that includes an elevator car and a rope, connected to the elevator car and by which the elevator car is hoisted. The hoist machine includes a motor, an output shaft projecting from the motor, and a traction sheave, for frictionally engaging and moving the rope. The traction sheave is of integral, unitary construction with the output shaft. In one embodiment, the traction sheave can include a traction surface and a plurality of annular flanges projecting from the traction surface. The output shaft can also include motor and brake interface features.
A further aspect of the invention relates to a hoist machine for an elevator system that includes an elevator car and a rope, connected to the elevator car and by which the elevator car is hoisted. The hoist machine includes a hoist motor, having an output shaft on which are disposed a pair of bearings, for rotationally supporting the output shaft, and a traction sheave, for frictionally engaging and moving the rope. A single bearing frame is provided, having both a proximal opening and a distal opening aligned with one another for respectively receiving and supporting the proximal bearing and the distal bearing.
The proximal opening and the distal opening are preferably fixed positionally relative to one another. Also, the bearing frame is preferably of unitary construction. The bearing frame can include a pair of bearing stands, each of which defines one of the distal opening and the proximal opening, and at least one arm interconnecting the bearing stands. Preferably, the traction sheave is located between the bearings on the output shaft.
A still further aspect of the invention relates to a hoist machine for an elevator system that includes an elevator car and a rope, connected to the elevator car and by which the elevator car is hoisted. The hoist machine includes a hoist motor, having an output shaft on which are disposed a pair of bearings, for rotationally supporting the output shaft, and a traction sheave, for frictionally engaging and moving the rope. A bearing frame is provided, having a proximal opening and a distal opening aligned with one another for respectively receiving and supporting the bearings. At least one of the proximal opening and the distal opening is sized so that the traction sheave on the output shaft fits longitudinally therethrough.
It is preferably the proximal opening that is sized so that the traction sheave on the output shaft fits longitudinally therethrough. In practice, both the proximal opening and the distal opening should be sized so that the traction sheave on the output shaft fits longitudinally therethrough. Preferably, the traction sheave is located between the bearings on the output shaft. It is also preferable that the bearing frame be of unitary construction.
The foregoing and other objects, features and advantages of the present invention become more apparent in light of the following detailed description of the exemplary embodiments thereof, with reference to the accompanying drawings in which like reference numbers refer to like elements throughout.